SpecialEvents.java

    public static class RandomChestSpawnListener extends BukkitUtil.Listener {
        private final Consumer<Location> chestLoc;
        private final String prefix;
        private final long delay;
        private final int randChance;

        public RandomChestSpawnListener(Consumer<Location> chestLoc, String prefix, long delay, int randChance) {

            this.chestLoc = chestLoc;
            this.prefix = prefix;
            this.delay = delay;
            this.randChance = randChance;
        }
        long lastSpawn = System.currentTimeMillis();
        @EventHandler
        public void onChunkLoad(ChunkLoadEvent event) {
            long now = System.currentTimeMillis();
            Chunk chunk = event.getChunk();
            if (EmpireServer.getServer() == EmpireServer.STAGE || Util.isTownWorld(chunk.getWorld()) || chunk.getWorld().getEnvironment() != World.Environment.NORMAL) {
                return;
            }

            if (now - lastSpawn > delay && NumUtil.rand(1, randChance) == 1) {
                final int chunkX = chunk.getX();
                final int chunkZ = chunk.getZ();
                int x = NumUtil.rand(chunkX << 4, ((chunkX + 1) << 4) - 1);
                int z = NumUtil.rand(chunkZ << 4, ((chunkZ + 1) << 4) - 1);
                final Block block = chunk.getWorld().getHighestBlockAt(x, z).getRelative(BlockFace.UP);
                if (block.getType() == Material.AIR && Residence.getResidence(block) == null) {
                    block.setType(Material.CHEST);
                    final Location loc = block.getLocation();

                    chestLoc.accept(loc);
                    lastSpawn = now;
                    for (Player player : chunk.getWorld().getPlayers()) {
                        if (Util.isWithinDistance(loc, player.getLocation(), 16*13)) {
                            Util.sendMsg(player, prefix
                                + NumUtil.rand((chunkX << 4) - 8, (chunkX << 4) + 24)
                                + ","
                                + NumUtil.rand((chunkZ << 4) - 8, (chunkZ << 4) + 24)
                            );
                        }
                    }
                }
            }
        }
    }